An ultrasonic bath is unproblematic on modern writing instruments, provided the pen does not stay in the bath too long; on wood or celluloid devices it is to be advised against. Gentle routine cleaning succeeds through repeated filling with water until no ink residues come out. Water-soluble royal-blue inks dissolve again with water even after long drying; with coloured inks cleaning is more difficult and requires partly a complete disassembly and mechanical cleaning of the feed. The rumour that Montblanc ink contains particularly many and firm particles does not apply; it counts among easy-flowing inks. Care is required for all brands and price levels. Waterman inks have a musty smell but are flow-technically good but should, on Waterman nibs, occasionally cause corrosion at the grip-section end.